Glasseelmarket.com - Waarddijk 6 A - 1704 PW Heerhugowaard - Netherlands - tel: +31 226 321099 - mob: +31 646 166 670
Tips for restocking:
The clients schedule, catches and available flights will be considered for the final planning of the date of delivery. The time of delivery is more
flexible if the glass eels can be transported by road.
Serious frost may not damage the glass eels after the restocking has been done.
Food must become available in the early Spring when micro organisms start growing.
Glass eels have no problems with temperatures close to 0 Celsius and will stay passive, but a quick start of the feeding process is preferred
for their survival. They have not been feeding for a long time and have lost quite some bodyweight. Resistance against diseases has
decreased. Feeding will strongly improve their condition and they will start growing rapidly.
The exact location of delivery is as the client wishes if transport is done by road. Delivery can be at one spot, but we can also deliver at
several spots for this restocking project.
Restocking at many spots is preferred. So unexpected incidental dangers will be less damaging. These dangers can be predators (fishes,
birds, prawns, lobsters etc.), diseases, cold water, sun, mechanical structures, pollution etc. A spot with hiding places (plants) and shallow
water is much better as deep cold water.
Putting a handful of glass eels in the water every 50 m just along the side between plants or reed is advised.
But any delay must be avoided, so the glass eels will not suffer from lack of oxygen, ammonium, changing temperatures etc.
restocking: glass eels
Restocking must be performed as long as the natural migration of glass eels has
not been recovered as the result of an again growing natural stock in inland waters.
Restocking with glass eels will improve the eel stock and therefore the number of
escaping silver eels, resulting in more glass eels.
Most of the migrating glass eels are just food for other fish and only a small
percentage will survive. Catching these glass eels en transporting these to the
inland waters and thus avoiding all these predators will seriously increase the
survival rate and will result in much more grown eels.
First or last glass eels:
In every catching area the first glass eels are usually large, still completely glassy,
come from cold water and are free from diseases.
The last glass eels are usually small and already pigmenting, come from warmer
water and may carry several types of parasites, bacteria etc.
Glass eels from France and England count first 2200, later 3200 pcs/kg, from the
west and south of Spain first 3000, later 4000 pcs/kg.
Catching and handling methods:
Only hand nets are allowed in England. The holding and selection systems are
quite professional. Therefore the quality of the English glass eels is usually
In Spain the same methods are mostly used, resulting in very good quality.
Also the south of France produces good quality this way, but trawling with small
boats is common practice in mid France, which may damage the fish. Not
frequently emptying the nets or fast trawling increase the damages.
These damages, often not visible, can result in mortality, sooner or later.
The catching methods and quality are described for the different countries as we
have experienced these through the years. Different situations and results often
Often small eel fingerlings, raised
in farms from glass eels, are used
for restocking. About 75 - 80% of
these glass eels will grow to
fingerlings of 5 - 10g each. So the
survival rate of these glass eels is
again much better as in nature.
We do not know yet how well
these fingerlings have protected
themselves against diseases.
Raised in high quality water they
will not carry PCB’s, dioxins etc.
But the resistance against all kind
of diseases might not have been
This resistance is mainly build up
when they are still very small and
start migrating and feeding in
nature and they meet all kinds of
parasites, bacteria etc.
But these glass eels skip that
period, because they are in the